Combined manual block and train identity system



F. x. REES EI'AL 2,794,117

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May 28, 1957 T Filed Aug. 28-, 1952 United States Patent COMBINED MANUAL BL OCK AND TRAIN IDENTITY SYSTEM Frank x. Rees, Chili, and Clark A. Pickell, Rochester, N. Y., assiguors to General Railway Signal Company, Rochester, N. Y.

Application August 28, 1952, Serial No. 356,758

8 Claims. (Cl. 246-) This invention relates to the control and indication of railway signalling devices by carrier currents and also the reporting of train passage and identity by carrier currents over the same conducting medium, and more particularly pertains to the remote control of a manual block signal and the remote indication of a train having passed that signal.

The usual manual block signal is controlled locally by an operator Who may clear the signal upon instructions provided he has received word that the block is vacated, and who restores that signal to stop after the complete passage of the train. This type of manual control thus provides that both the engineer at the front of the train and the conductor at the rear of the train can observe the indication of the signal.

In addition, the local operator upon observing the complete passage of the train beyond the signal can then notify the next adjacent operator by suitable communication means that the block in the rear of that signal has been wholly vacated. Obviously, one of the basic principles of manual block signalling is the observance by the local operator of the complete passage of a train out of a given block.

With the above principles in mind, it will be readily understood that the remote control of a manual block signal involves among other things at least two distinct problems. In the first place, the manual block signal must be so controlled that it will never assume a clearing position because of erroneous operation of the communication system employed. The second point is that the mere reporting of the passage of a train is insufiicient and means must be provided to indicate whether or not the complete train has vacated the block.

The present invention proposes to provide the safe remote control of a manual block signal and to provide means for reporting the passage of a train as a whole. Generally speaking, and without attempting to define the exact nature and scope of the present invention, the proposed organization provides that a manual block signal shall be remotely controlled by the coding at different rates of a carrier frequency transmitted over a suitably available line circuit and that the response of such signal shall be indicated by a repeat type of coding of a different carrier frequency transmitted over the same line circuit.

It is also proposed that the rear end of each train be equipped with means which will inductively affect a local train identifying means in such a way that the passage of the train and its identity will be distinctly registered at the signal location only providing the complete train has passed that point. It is then proposed that this train identity shall be transmitted to the remote control point over a coded carrier current of a still different frequency, and in this way advise the operator both of the passage of the train and its identity. Since the train-carried identifying means is located on the rear end of the train, it is obvious that the whole train must pass the point before such means can act upon the local pick-up means. In providing the control and indication facilities above mentioned, the possibility of a cross-talk type of failure in the carrier current apparatus is obviated by reason of the fact that the train reporting indication can be trans mitted only provided the signal is controlled to stop by a code rate diiferent than the rates used to identify the different trains.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings, and in part pointed out as the description progresses.

In describing the invention in detail, reference will be made to the accompanying drawings, in which like reference characters designate corresponding parts throughout the several-views, andin which:

Fig. 1 is a diagrammatic representation of the circuits and devices employed at the control ofiice of a system embodying the present invention; and

Fig. 2 is a diagrammatic representation of the circuits and devices employed at the field station of a system embodying the present invention' For the purpose of simplifying the illustration and facilitating the explanation, the various parts and circuits constituting the embodiment of the present invention have been shown diagrammatically and certain conventional illustrations have been employed, the drawings having been made more with the purpose of making it easy to understand the principles and mode of operation than with the idea of illustrating the specific construction and arrangement of parts that would be employed in practice.

The symbols and are employed to indicate the positive and negative terminals respectively of suitable batteries or other sources of direct current; and the circuits With which these symbols are used, are assumed to have current flowing in the same direction. However, it is to be understood that should alternating current be employed instead of direct current, such symbols would merely indicate the relative instantaneous polarities.

Referring to Fig. 1, it will be noted that the control office equipment includes a signal control lever SGL which is normally in a stop position S and is operable to a clearing position G or a caution position Y. A repeating relay of the stick circuit type is provided for each position of the lever including relays SLP, YLP and GLP. Also, the lever SGL has associated therewith signal indicators G, R and Y for the respective positions of the lever; and when any one of these indicators is illuminated it conveys the information to the operator that the manual block signal SG in the field is controlled to display a corresponding aspect.

In addition there are three code oscillators CT, 1120GT and 180CT which are respectively initiated when the signal control lever SGL is operated to its positions S, Y and G. These code oscillators may be of any suitable type, but for convenience have been assumed to be of the type disclosed in the prior Patent No. 2,351,588 granted to O. S. Field on June 20, 1944. These oscillators have associated therewith suitable contacts which operate at their respective rates such as 75, and times per minute.

It is assumed that a line circuit including line Wires 4 and 5 extends to the field station disclosed in Fig. 2. The oflice apparatus includes a carrier frequency transmitter 6 for transmitting a carrier frequency f1 whenever its control (or keying) circuit is closed; and this control (or keying) circuit is closed at difierent rates as selected by the lever repeating relays SLP, YLP and GLP, in a manner later to be described.

The control oifice equipment also includes a carrier frequency receiver 7 for the frequency f2 and another carrier receiver for the frequency f3 both of which are also connected to the line wires 4 and 5. A relay F2 is operated by the reception of a carrier to a dropped away position and is picked up upon the cessation of the carrier. in this way, it is operated at the rate at which the carrier f2 is coded at the field station. A similar relay F3 is associated with the carrier frequency receiver 8. In brief, each receiver normally energizes its output relay F, but causes it to be released whenever a carrier frequency is received.

Decoding transformers 9 and 10 are respectively associated with the relays F2 and F3. A code responsive relay CDR is associated with the lever repeater relays and is energized whenever the code received by the car-' rier frequency receiver 7 corresponds to the code transmitted by the carrier frequency transmitter 6 in amanner later to be described. This relay CDR is preferably a polarized relay which will respond to only. one direction of current flow. One suitable relay of this type is disclosed in the prior Patent No. 2,414,583 granted January 21, 1947, to G. E. Duffy. This relay CDR is indicated as having slow release characteristics which. may bev accomplished in any suitable way,zsuch as by copper slugs, or a winding short-circuited through afront contact of the relay. This provides that code pulses will pick the relay up, and once the relay is up it will remain steadily picked up so long as code pulses are received.

The decording transformer 19'. supplies energy to the decoding units 120DU, 186DU,.270DU and 409DU, so that the rate of the code then being received will be effective through the corresponding decoding unit to actuate its respective decoding, relay. These relays 120DR, 180DR, 27tiDR and 4961311 are each provided with contacts for controlling identity indicators designated respectively 120, 180, 270 and 400. In addition these decoding relays are also provided with. local stick circuits which maintain the relays picked up once they have picked up in response to a code until a reset button RS is manually actuated. This reset button RS is of the self-restoring push button type. The decoding units are assumed to be of the conventional tuned type with rectifiers to supply unidirectional current to their respective relays when the proper code rate is received;

Referring to Fig. 2, it will be observed that the line circuit including line wires 4 and 5 have connected thereto a carrier frequency receiver 50'for the carrier frequency f1. This receiver has associated therewith a relay F1 which responds to the reception of the carrier to repeat the different code rates in the same way as explained for the relays F2 and F3 at thecontroloifice. Two carrier frequency transmitters 51' and 52 are also provided for respectively transmitting on frequencies f2 and f3.

The carrier frequency receivingrelay F1 operates contact 54 to supply pulses throughthe decoding transformer 53 to control a decoding relay CD and the decoding units 180DU, 120DU and 75DU, as will later be described. These decoding units respectively control the decording relays 180D, 120D, and 75D, and in turn control the signal control relays RR, YR' and GR. For convenience in the illustration these signal control relays directly control the lamp R, Y and G of'a color light signal SG which is assumed to be of the manual block type governing the entrance of traffic into a block of nonsignalled territory. For this reason, this signal SG has associated therewith the symbols MB. It is of course understood that any other suitable-type of signal might be employed such as a search light signal as disclosed for example in the Patent No. 2,376,534-to O. S. Field.

When the signal SG displays an aspect corresponding to its control code, the correspondence relay CCR is energized and causes a repeat-code to be transmitted by the carrier frequency transmitter 51 over the carrier frequency f2 to the control office.

Referring to the track layout shown in Fig- 2, it will be seen that signal SG governs the entrance of traffie into non-signalled territory from a territory which is equipped with the conventional automatic or semi-automatic signals, as indicated by the symbols.

In advance of the signal SG is a relatively short track circuit having a track relay ATR; while in the rear of this signal SG is another track circuit having a track relay BTR. These two track relays have associated therewith an approach relay AR. In addition, there are repeater relays AP, APP and ATPS to provide timing operations and a directional control for the identity transmission as will be discussed in detail hereinafter.

Just to the rear of the signal SG at a suitable distance is located the pick-up coil 49 of an inductive type identity or train describing system which includes an identity receiver and amplifier. This identity or train describing system may be of any suitable type; but for convenience, it is assumed to be of the type disclosed in the prior application of Kendall and Zaifarano, Serial'No. 206,395, filed January 17, 1951, now a Patent No. 2,693,525- granted on-November 21, 1954. This identity receiver and amplifier is set into operation upon the approach of a west bound train as controlled by the track relay ATR.

and the approach relay AR; and it is distinctively controlled upon the passage of a tuned coil of any one of a plurality of different frequencies to actuate a relay for the corresponding frequency suchas relays R, R, 270R and 400R. In addition, an indication relay IR is actuated upon the passage of any coil of any of the different frequencies for the purpose of providing a check and restoration feature later to be described. Asso-' ciated with this relay is a repeater of the slow actingtransmitted providing the train is moving from rightto left as indicated by the arrow adjacent the trackway pick-up coil. In other words,-it is desired to indicate to the operator when a train has completely leftthe nonsignalled territory so that conditions are perfectly safe for him to clear the manual block signal SG to allow a train to enter such non-signalled territory. When a train is moving in the opposite direction any actuationof the identity receiver and amplifier is" ineffective by reason of the actionof the track stick repeater relay ATPS'.

It is belived that thenature of the invention, its advantages and characteristic features can be' best understood With further description being set forth from" the standpoint of operation.

Operation Normal c0nditions.-Under the normal conditions illustrated, the signal lever SGL is in its stop position S to hold the signal SG at stop. Thus, a normal stop code of the 75 rate is transmitted over the carrier frequency f1 while the signal is at stop, so-thatan indication of the signal condition canbe transmitted back to the con-- trol ofiice on the carrier frequency 12.

More specifically, with the signal'lever SGL in its stop position S, its contact 11 connects to the left=hand tenminall of the lever repeating relay- SLP, which has connected to its right-hand terminal through its'own front contact 12. In other'words, the relay SLP'is'held up through a stick circuit, having been picked upupon' therestoration' of the signal lever SGL to a stopposition' in a manner later= to'be described.- The contact'13 of the' sig'nal lever SGL directly applies (-1-) to'the'code oscillator 75CT so that it is operating continuously; Since the front'cont-a'ct 14 of the lever repeating relay SLPis closed, the oscillating contact 15 intermittently completes a controlor keying circuit for th'e carrier frequency transmitter 6 at the75 code rate to thereby cause 'the'intermittent transmission of the carrier frequency 11 over the line wires 4 and 5.

At the field station shown in Fig. 2, the carrier frequency receiver 50 receives the carrier frequency f1 at the 75 code rate and operates the output relay F1 at such rate. This relay F1 through its contact 54 causes the direction of the current in the primary winding of the decoding transformer 53 'to be reversed at the 75 code rate which induces pulses in its secondary winding that are rectified by contact 55 to successively energize the decoding relay CD in the same direction. Since this relay CD is slightly slow release, it remains picked up between successive energizations at the 75 code rate or any of the higher code rates. The closure of its front contact 56 allows the upper secondary winding of the decoding transformer 53 to supply pulses to the bus wires 57 and 58 to which are connected the decoding units 180DU, 12tiDU and 75DU. These decoding units are of the conventional type including a resonant circuit and rectifier arrangement such that an output is supplied to the respective decoding relay D suificient to operate that relay only when the corresponding code rate is received. The reception of the 75 code rate causes the decoding unit 75DU to supply actuating energy through contacts 59 60 and 61 to pick up the decoding relay 75D. The closure of its front contact 62 energizes the red repeating relay RR through an obvious circuit.

With the signal SG displaying stop in accordance with its control, a circuit is completed for the correspondence relay CCR from through a circuit including front contact 64 of relay RR, front contact 65 of relay 75D, windings of relay CCR, to Thus, front contact 66 of relay CCR is closed so that the repeated operation of front contact 67 of relay F1 causes the carrier frequency transmitter 51 to be intermittently effective at the same 75 code rate to transmit the carrier frequency 2.

The reception of such 75 code rate over the carrier frequency f2 is received by the carrier frequency receiver '7 and operates its output relay F2 accordingly. The intermittent operation of the contact 16 of relay F2 of course causes the energy in the primary winding of the decoding transformer 9 to be intermittently reversed at the same rate. Thus, the secondary winding of the decoding transformer 9 supplies energy to the decoding relay CDR through front contact 17 of relay SLP because these pulses occur at the same rate of operation and in unison with the operation of the coding contact 18 of the oscillator '75CT.

It is noted that these current pulses for relay CDR are all in the same direction because of the rectifying effect of contact 18 operating in unison with contact 16.

'Also, the direction of the current is proper to cause response of the polarized relay CDR. However, if there should be an erroneous cross-fire between the transmitter 6 and the receiver 7, the operation of the contact 16 would be at the same rate as the code contact 18, but it would be 180 out of phase compared to proper op eration. This would cause pulses of the opposite polarity to be applied to the relay CDR and it wouldnot respond to such pulses. In this way, the relay CDR is made to operate only in response to indication code pulses received over the carrier frequency f2.

The picked up condition of the relay CDR because of its repeated energizations in response to a proper code, closes front contact 19 to supply energy from through front contact of relay SLP to the red signal indicator R. This advises the operator that the signal SG in the field is actually displaying a stop (red) aspect.

Under these normal conditions, the train identity and reporting apparatus is at rest and none of the identity indicators (Fig. 1) are illuminated.

Passage of a train out of non-signalled terrilory.Let us assume that a train is moving from right to left in the non-signalled territory and is approaching the location of the manual block signal SG. When it occupies the track section including the track relay ATR such track relay drops away. The approach relay AR is normally energized through front contact 68 of relay BTR and front contact 69 of relay ATR, so that the release of the track relay ATR causes the release of relay AR. This closes back contact 70 of relay AR to initiate operation of all the associated code oscillators. Also, the closure of back contact 71 applies energy to the identity receiver and amplifier to set it into operation in readiness to receive a train identity.

The closure of back contact 72 of relay ATR energizes the approach repeater relay AP through an obvious circuit. In turn the closure of front contact 73 of relay AP energizes the repeater relay APP. Both of these relays have slow release characteristics for reasons later to be discussed. The opening of front contact 74 of relay ATR does not cause the release of the track stick relay ATPS because of the closure of its stick circuit from through back contact 75 of relay IR, and front contact 76 of relay ATPS.

Let us assume that the train continues in its left-hand direction and passes into the track section having track relay BTR. So long as the train is in that section, the relay AR is of course caused to be deenergized because of open front contact 68, even though the train passes out of the adjoining track section allowing the picking up of the track relay ATR and the closure of its front contact 69. When the train has completely passed out of the adjoining track section allowing track relay ATR to pick up, it is apparent that the relay AP is deenergized and begins to drop away which in turn would release the relay APP and allow it to drop away opening front contact 77 included in the identity transmitting circuit. The release times of these two relays AP and APP are so selected as to measure a predetermined time, such as in the order of three to six seconds, and during this time which begins with the train leaving the track section having track relay ATR, the rear end of the train must register its identity by passing over the pick-up coil 49. Assuming that the train is complete and the train identifying coil at the rear end of such train passes over the pickup coil 49, then the relay corresponding to that identity, such as the relay 120R, for example, is picked up and at the same time the relay IR is picked up.

The closure of front contact 78 connects through back contact 79 of relay 180R and front contact 80 of relay 120R through the lower winding of relay 120R, to Thus, the relay 120R is maintained picked up dependent upon relay IR even though its control through the identity receiver and amplifier is only momentary. Also, the closure of front contact 7 8 applies energy through front contact 81 of relay lRP to the lower winding of relay 1R to maintain it energized although its control is only momentary through the identity receiver and amplifier.

The opening of back contact 82 of relay IR deenergizes its repeater relay IRP, but this relay is slow releasing to a considerable degree, such as in the order of three seconds. At the end of its release period, it opens front contact 81 to release the relay IR and in turn Opening front contact 78 to release the relay 120R; but before considering what happens when this time has run out, there are several conditions to observe in order to see how the timing of relay IRP determines the identity ex-. ecution time.

It should also be noted that the picking up of the relay IR opens back contact '75 which is included in the stick circuit of the relay ATPS. However, for this direction of travel, relay IR is not picked up until the track section having track relay ATR is vacated so that front'contact 74 connects through front contact 85 of relay APP and front contact 76 of relay ATPS to the windings of relay ATPS. This alternate stick circuit maintains relay ATPS energized and with its front contact 86 closedeve'n' 7 though'back contact 75 is opened. Also, the relay APP is--held up by reason of a stick circuit closed from through a circuit including front contact 83 of relay ATPS, front contact'82 of relay IR, front contact 84 of relay APP, windings of relay APP, to In this way the front contact 77 of relay APP is maintained closed.

Thus, during the release time of the relay IRP, an identity execution circuit is closed from through front contact 78 of relay IR, back contact 87 of relay 400R, back contact 88 of relay 270R, b ack cont-act 39 of relay 180R, front contact 90 of relay 120R, coding contact 91 of code oscillator 120CT, front contact 86 of relays ATPS, front contact 77 of relay APP, front contact 92 of relay ATR, front contact 93 of relay 75D, carrier frequency transmitter 52., to The intermittent energization of the transmitter 52 over this circuit at the 1 2 code rate thus causes the carrier frequency 3 to be transmitted over the line wires 4 and 5 at the 120 code rate. This continues onlyuntil the relay IRP drops away and causes the release of relays IR, 120R and APP. More specificially, the opening of front contact 81 deenergizes relay IR which in turn opens front contact 78 to open the energizing circuit for relay 120R and to also open the identity execution circuit. The release of relay IR opens front contact 82 to allow relay APP to drop away after a short interval; but back contact 75 is now closed so that the stick circuit for relay ATPS is maintained closed. When the relay APP releases, the front contact 77 is again opened. However, it will be noted that the control of the carrier frequency transmitter 52 at the 120 rate ceases as soon as front contact 78 is open. Also, the closure of back contact 82 of relay IR causes the reenergization of relay IRP in readiness for another operation. From the above description, it will be understood that the relay ATPS is maintained picked up throughout the passage of the west bound train and the registration and transmission of its identity.

At the control ofiice (Fig. 1), the carrier frequency f3 is received by the carrier frequency receiver 8 so that the output relay F3 is operated at the 120 rate. This causes contact 21 to alternately reverse the direction of energization of the decoding transformer It at the corresponding rate, so that pulses from the secondary winding of this transformer is fed through front contact 22 of relay SLP to the bus wires 23 and 24 to the decoding units DU. This particular rate causes the decoding unit IZQDU to supply pick-up energy for the decoding relay 120DR while that rate is being received. But the relay 120DR has a stick circuit closed from and including reset button RS in its normal position, front contact 25 of relay 120DR, windings of relay TZGDR, front contact 26 of relay 120DR, resistor 27, to This stick circuit maintains the relay 120DR energized until the reset button RS is manually actuated although code transmission from the field station shortly ceases. The closure of front contact 28 of relay 120DR supplies to the 120 identity indicator.

It is assumed for the purposes of the present disclosure that the system of this invention is associated with a conventional CTC system for the remote control and indication of the related switch, signals and track circuits. Thus, the track indicators AI and BI are respectively illuminated when the corresponding track sections are occupied by the passing train. But the illumination of the 120 identity indicator additionally advises the operator of the train identity and that the entire train has vacated the nonsignalled territory. This gives the operator the necessary information so that he can freely clear the signal S6 to allow an eastbound train to enter the non-signalled territory or he can advise another operator that such territory is vacated so that another west bound train can be permitted to enter.

From the above description, it is apparent that the identity coil on the rearof the train must pass the pickup coil 49 within a limited time after it leaves the track section having track relay ATR, which time is measured by the release of relays AP and APP. Also, the identity is transmitted for only a limited time as measure-d more particularly by the release of relay IRP. The storage of the identity at the control oflice may remain as long as the operator desires, since it is dependent upon him to actuate the button RS whenhe has suitably made a record of the passage of the train. It should of course be understood that any one of four different train identities may be given by the apparatus shown, and also that additional identities may be provided if desired by the provision of additional apparatus sirnilarly constructed.

Clearing of sign al.-Let us assume that the operator desires to cause the signal SG to display a clear (green) aspect for a train to proceed into the non-signalled territory. To do this, he actuates the lever SGL to its lefthand position G which deenergizes the relay SLP and also deenergizes the code oscillator CT. The opening of front contact '14 of relay SLP of course prevents the further transmission of the 75 code over carrier frequency f1, while the opening of front contact 17 prevents further pulses to reach the relay CDR from the transformer 9 as caused by the operation of cont-act 18. In any event, the cessation of the transmission of the 75 code over frequency f1 to the field station causes the cessation of the operation of relay F1 at the field station so that code pulses are not repeated over the carrier frequency f2 to operate relay F2 in the control office. For these several reasons, the relay CDR releases after a short period closing back contact; 29. It is noted that the opening of front contact 20 of relay SLP deenergizes the (red) signal indicator R conveying to the operator that the signal'SG no longer displays a red aspect in conformance with a control.

At the field station (Fig. 2), the cessation of the operation of the output relay F1 at the 75 code rate causes the relay CD to be released opening contacts 56 and 59. Also, no pulses can be applied to bus wires 57 and 58 when contact 54 is not following a code. In any event, relay 75D is released opening front contact 65. Also, the opening of front contact 62 deenergizes relay RR to open front contact 64. Thus, relay CCR is assured of being deenergized to open front contact 66 and prevent the transmission of a carrier frequency f2 even though relay F1 maintains contact 67 steadily closed. It should be noted that the signal SG continues to display a red aspect by reason of lamp R being energized through back contacts and 101.

The closure of back contact 29 of relay CDR in the control office (Fig. 1) completes a circuit for the picking up of the lever repeater relay GLP from contact 11 in a left-hand position, windings of relay GLP, back contact 30 of relay YLP, back contact 12 of relay SLP, back contact 29 of relay CDR, to As soon as the relay GLP picks up, it closes its front contact 31 to complete its stick circuit to render it wholly dependent upon the lever contact 11. The picked up condition of the relay GLP then completes the control of the carrier frequency transmitter 6 through back contact 14 of relay SLP, back contact 32 of relay YLP, front contact 33 of relay GLP, coding contact 34 of code oscillator CT. Thus, the carrier frequency transmitter 6 so controlled as to cause the carrier frequency ii to be transmitted at the 180 code rate, which is received at the field station by the carrier frequency receiver 50.

The operation of the output relay F1 at the 180 code rate results in the reenergization of the relay CD and the application of pulses to the buses 57 and 58 so that the decoding unit 180DU will supply pick-up energy to the decoding relay 1801). This causes the closure of a pick-up circuit for the green signal control relay GR from through a circuit including back contact 62 of relay 75D, back contact 94 of relay 126D, front contact 95 of relay 180D, windings of relay GR, to This causes the energization of the green lamp of signal SG from through back contact 63 of:

relay RR, back contact 96 of relay YR, front contact 97 of relay GR, lamp G, to This causes the signal SG to display a proceed (green) aspect so that the train may pass into the non-signalled territory.

With the relay GR picked up, a circuit is completed for the correspondence relay from and including front contact 98 of relay GR, front contact 99 of relay 180D, windings of relay CCR, to This causes front contact 66 to be closed to allow the control of the carrier frequency transmitter 51 to be intermittently closed at the 180 rate by contact 67 of relay F1. This coded carrier frequency f2 acts at the central oflice to operate the output relay F2 at the 180 rate so that relay CDR is by 180 rate code pulses in unison with the coding contact 35 because back contact 17 is closed, back contact 36 is closed, and front contact 37 is closed. In other words, the relay F2 must operate in unison with the code oscillator 180CT in order for the relay CDR to be picked up. The picking up of this relay then opens back contact 29 and closes front contact 19 to complete a circuit through front contact 38 of relay GLP to energize the signal indicator G (green) to advise the operator that the signal SG is displaying an aspect corresponding to the control transmitted to it.

Passage of east-bound train.When the east-bound train passes the signal 56, the signal SG is not restored to stop but remains in its clear position until the operator manually causes it to go to stop after the train has left the track section having track relay BTR. This assures that the trainman at the rear of the train will be able to see the signal at clear and know that the train entered a clear block.

As previously described, the. conditions of the track circuits are indicated in the control ofiice by communication means not shown. Thus, as the train passes through the two successive track sections having track relays BTR and ATR, such fact is indicated to the operator in the control ofiice by the successive illumination of the indicators BI and AI. In this way, the operator knows that the train has completely passed the signal SG when the indicator lamp BI becomes unilluminated; and at thistime the operator can restore the signal control lever SGL' to its stop position S to restore the control of the signal SG to its normal condition.

More specifically, the restoration of the contact 11 to its normal position deenergizes the relay GLP which opens the circuit for the relay CDR, and opens front contact 33 to stop transmission of the 180 code rate. Also, the contact 13 removes energy from the code oscillator ISQCT. When the relay CDR closes it back contact 29 after a short interval of time sufficient to allow relay CD in the field to release, the relay SLP is picked up as previously described; and since the contact 13 energizes the code oscillator 75CT, the 75 code rate is caused to be transmitted by reason of front contact 14 all as previously described. It will, of course, be apparent that the opening of front contact 38 of relay GLP deenergizes the signal indicator G and the signal indicator R cannot become energized even though front contact 20 is closed until the relay CDR is again picked up by the reception of code pulses. This reenergization of relay CDR does not occur until the normal conditions have been established at the field station to cause the carrier frequency f2 to repeat the 75 code rate received by the output relay f1 in a manner previously described.

One thing to note at the field station of Fig. 2, is that the cessation of the 180 code rate causes the relay CD to be deenergized and open contact 59 to immediately release the decoding relay 180D; and this occurs before the relay CDR at the control office has released and allowed relay SLP to pick up. Ordinarily, the decoding relays, such as relay 180D, being controlled through a conventional decoding unit, are rather slow to release, but by selecting the circuits for these decoding relays through a contact of the relay CD, they are released 10 more quickly causing the control of signal SGto be relatively quick in its response.

The opening of front contact 95, of course, deenergizes the relay GR to deenergize the lamp G of the signal SG; and also the opening of contact 99 of relay- 180D deenergizes the correspondence relay CCR so that the carrler frequency fl is not transmitted until correspondence is again established.

The receipt of the code rate again causes the relay CD to be picked up and in turn the decoding relay 75D. The relay RR is again energized and the circuit for the correspondence relay CCR is closed through front contacts 64 and 65, to cause the carrier frequency f2 to be transmitted to the control office at the 75 code rate to again effect the energization of the relay CDR and the illumination of the signal indicator R to advise the operator that the signal SG has been restored to its stop conditions.

When the train passes the signal SG with its train identity coil at the rear, the operation of the identity receiver and amplifier does not cause the transmission of a train identity to the office by reason of the fact that the directional stick relay ATPS positively prevents the closure of the identity transmitting circuit.

Perhaps this operation will be best understood by consldering what happens at the field station of Pig. 2 during the passage of this cast-bound train. The deenergizatron of the track relay BTR, of course, deenergizes the relay AR which in turn initiates the code oscillators in the usual way. But when the train occupies the track sectron having track relay ATR, the relays AP and APP are successively picked up to close contact 77. However, the contact 92 is open at this time. Thus, when the train identity coil passes the pick up coil 49, the appropriate identity relay, such as 270R, is picked up together with the relay IR. The opening of back contact 75 causes the relay ATPS to immediately drop away because the front contact 74 of relay ATR is open. The immediate dropping away of the relay ATPS opens front contact 86 so that the identity transmitting circuit is further held open and will be until this relay ATPS is again picked up. Assuming that the train continues on its way, it is apparent that the relays AP and APP will remain picked up until the track relay ATR is reenergized, but the stick circuit for the relay APP cannot be closed because of the open condition of front contact 83. Of course during this time the relay IRP has been deenergized, and it may or may not become dropped away before the train leaves the track section having track relay ATR. This is immaterial because the closure of back contact 75 cannot pick up the relay ATPS.

, Assuming that the relay ATR is picked up after the train leaves the associated track section, the closure of front contact 74 cannot pick up the relay ATPS until the relays AP and APP have been successively released. When this takes place, the pick up circuit for relay ATPS is closed through front contact 74 and back contact 85.

From the above description, it will be seen that the closure of front contact 92 does not complete the identity transmitting circuit even though the identity relays have not been released, because the front contact 86 is open until the train has left the track section for a time. Also, the relay ATPS cannot be picked up until the relay APP is dropped away with the resultant opening of front contact 77. Thus, regardless of the particular timing periods, the sequence of operation is such that the identity transmitting circuit is positively held open during the passage of an east-bound train.

From the above description, it is apparent that a suitable control and indication organization for a manual block system has been employed to assure that the manual block signal is cleared only when a proper coded.

carrier frequency is received at the signal location. The system is also organized so that a new control code cannot be transmitted until the old code has ceased to be;

transmitted for a predetermined period of time. There is also means to check that the repeated indication code is received as a result of the repeat at the field station instead of a local cross-fire between the transmitter and receiver at the control office. This is accomplished by the use of a polarized relay to check the operation of the code transmitter in unison with the code being received.

The system of the present invention also provides train identity responsive means at the field station which can transmit distinctive codes over a carrier frequency to the control office only provided the associated manual block signal is controlled to display a stop aspect. In addition, the train identity can be transmitted only as a train is completely leaving the stretch of track into which the manual block signal governs, and this is effected by the use of directional responsive means adjacent to the signal.

Having thus described a carrier current control system for remote manual block signals and train identifying means as one embodiment of the present invention; it is desired to be understood that this form is selected to facilitate in the disclosure of the invention rather than to limit the number of forms which it may assume; and, it is to be further understood that various modifications, adaptations and alterations may be applied to the specific form shown to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention.

What We claim is:

1. In a remote control and indication system, a manual block signal governing traffic into a stretch of track having no automatic signals, communication circuit means for controlling said signal from a remote ofiice to give clear and stop signal aspects, a train identity responsive means adjacent said signal and automatically controlled by a passing train, other communication circuit means controlled by said train identity responsive means for transmitting the identity of a passing train to said remote office and directional responsive means adjacent the signal operating automatically for allowing said another communication circuit means to be effective only when a train is leaving said stretch of track.

2. In a remote control system, a manual block signal at a point remote from a control ofiice, a control lever at the control office, a first carrier frequency transmitting means at the control office and a first carrier frequency receiving means at the remote signal location, circuit means at the control office for transmitting different distinctive codes over said first carrier frequency in accordance with the position of said control lever, decoding means at said remote signal location controlled by said first carrier frequency receiver to control said associated signal in accordance with the code then being received, a train identity responsive means adjacent said signal, a second carrier frequency transmitting means at said remote signal location and a second carrier frequency receiving means at said office, said second transmitting and receiving means operating on a different frequency than said first transmitting and receiving means, means controlled by said train identity means for controlling said second carrier frequency transmitting means to transmit different codes over said carrier frequency in accordance with the identity of passing trains only if said first code receiving means is then receiving a code for controlling said signal to give a stop signal aspect, and decoding means at the control ofiice governed by said second carrier frequency receiving means to give a distinctive indication in accordance with the code then being received.

3. In a remote control system, a manual block signal remote from a control office, a first carrier frequency transmitting means at the control office and a first carrier frequency receiving means at said remote signal location, means at the control office for transmitting different distinctive codes over said first carrier frequency in accordance with the position of a control lever, decoding means at said signal controlled by said first carrier frequency receiver to control said signal in accordance with the code then being received, a second carrier frequency transmitting means at said remote signal location and a second carrier frequency receiving means at said office, circuit means at said remote signal location controlled in accordance with the condition of said signal and the code then being received for causing said second carrier frequency transmitting means to repeat the code then being received by said first carrier frequency receiving means only providing said signal has properly responded to the code then being received, means at the control office including a polarized relay and correspondence circuits for indicating when a repeat code is properly received by said second carrier frequency receiving means, and circuit means preventing the transmission of a different code by said first carrier frequency transmitting means until said polarized relay has become actuated to indicate lack of correspondence between the transmitted and received codes.

4. In a remote control system, a train identity responsive means adjacent a remote signal location being inductively responsive to the passage of an identifying tuned coil at the rear of a passing train, a carrier frequency transmitting means at said signal location and a carrier frequency receiving means at a control office, circuit means controlled by said train identity responsive means for transmitting a distinctive code in accordance with the received train identity for only a predetermined time, decoding means at the control office responsive to the code received by the associated carrier frequency receiver, said means having been once rendered active, remaining active until acknowledged by an operator, and indicators controlled by said decoding means.

5. In a remote control system, a manual block signal located at a remote point from a control office, a track circuit on each side of said signal, a directional stick relay controlled by at least one of said track circuits, a train identity responsive means adjacent said signal for also at times acting upon said directional stick relay, and communication means controlled by said train identity responsive means and said directional stick relay for transmitting a characteristic train identity to the control office for only those trains passing said signal in a particular direction.

6. In a remote control system, a train identity responsive means adjacent the trackway at a remote location and including a wayside receiver adapted to inductively cooperate With differently tuned train-carried coils to give distinctive controls in accordance with the identity of a train characterized by the tuning of its coil, a carrier frequency transmitter at said remote location and a carrier frequency receiver at a local ofiice interconnected by a communication channel, circuit means controlled by said train identity responsive means for only a predetermined time following the passage of each train for acting on said carrier frequency transmitting means to transmit a distinctive code rate corresponding to the identity of that train, decoding means at the local office controlled by said carrier frequency receiver to give a distinctive indication in accordance with each different rate code received.

7. In a remote control system, a train identity responsive means adjacent the trackway at a remote signal location including a wayside receiver adapted to inductively cooperate with differently tuned train-carried coils to give a distinctive control in accordance with the identity of a train as characterized by the tuning of its particular coil, a carrier frequency transmitting means at said remote signal location and a carrier frequency receiving means at a local office interconnected by a communication channel, circuit means controlled by said train identity responsive means for acting on said carrier frequency transmitting means for transmitting distinctive rate codes for each different train identity, said circuit means including directional responsive means so as to transmit a code. only when a train passes said remote signal in a direction opposite to that for which said signal governs traflic, decoding means at the local oflice controlled by said carrier frequency receiving means to give a distinctive indication for each diflerent rate code for the different train identities.

8. In a remote control system, a train identity means adjacent a remote signal location being inductively responsive to the passage of an identifying tuned coil at the rear of a passing train, detecting means for detecting that the track immediately in approach of said train identity means has become unoccupied, communication circuit means for transmitting a distinctive code in accordance with the train identity to a control oflice for only a limited time following the detection by said detecting means of the vacating of said track in approach of said train identity 14 means, decoding means at said control ofiice responsive to the distinctive code received over said communication circuit means, and indicating means selectively controlled by said decoding means for providing information to an operator of the identity of a train which has passed said remote signal location.

References Cited in the file of this patent UNITED STATES PATENTS 1,852,395 Benedict Apr. 5, 1932 2,122,229 Powell June 28, 1938 2,122,358 Preston June 28, 1938 2,252,525 Reid et al. Aug. 12, 1941 2,554,000 Baughman May 22, 1951 2,670,434 Groenendale Feb. 23, 1954 

